It has previously been proposed to provide an ankle brace, or orthopaedic apparatus including air inflatable bladders as shown in U.S. Pat. No. 4,280,489, in which the apparatus is intended to be worn within a separate shoe, and is inflatable with an external source of air pressure. In addition, various arrangements have been proposed for ventilating shoes by circulating air through the shoes. Typical patents showing this type of arrangement include M. Dunker U.S. Pat. No. 2,552,711; D. W. Oltrogge, U.S. Pat. No. 2,560,591; A. C. Crawford, U.S. Pat. No. 2,676,422; C. N. Eaton, U.S. Pat. No. 3,029,540; E. Karras, U.S. Pat. No. 3,331,146; and James Faiella, U.S. Pat. No. 4,414,760. These patents disclose the use of air pumping arrangements actuated by foot pressure for circulating air through a shoe, but do not include any orthopaedic support functions.
Additional prior art patents are noted as follows: First, the Gertsch German Patent No. 2,321,817, discloses a bellows pump system designed for ski boots. It is suggested that the pump be mounted in a recess in the bottom of the thick sole of the ski boot. To inflate or deflate the air chambers, a manually operated three-way valve is employed. One end plate of the bellows swings outward from the sole of the boot. To hold the bellows pump flush to the sole of the ski boot when not in use, a retaining hook is used in the Gertsch arrangements. Walkhoff, U.S. Pat. No. 4,703,403, discloses a pump system for a sports shoe, such as a ski boot. Walkhoff discloses that a pump system is recessed in the sole of his shoe and is activated by placing the pump on an "elevation" on the ski and activating the pump by a rocking motion of the foot. The Walkhoff drawing shows the activation side of the pump facing down for activation by engagement with the "elevation" on the ski. In the cases of both the Gertsch and Walkhoff devices, the pump is exposed through the sole of the shoe and if an attempt were made to walk or run with the shoes, mud, debris, or sharp objects may penetrate and/or clog the pumps and render them inoperative. Polus, et al., U.S. Pat. No. 4,763,426, discloses a sport shoe sole which has a number of cylindrical air chambers in the sole to improve the resiliency of the shoe. This patent discloses a pneumatic inflating device to inflate said cylindrical air chambers. This patent does not, however, offer any means for supporting the upper portion of the wearer's foot or ankle. The Polus specification mentions continuous "slight unloading" of the air chambers, indicating that leakage of the air chambers is undesired, and it appears that such leakage may be the reason that a pump is required in this Polus device. Moreover, it is clear that there is no indication whatsoever that such reduction in pressure over time is desirable, but only that it appears to be undesirable as constituting "unloading" of the air chambers.
In connection with athletic activities, such as football, basketball, tennis, or other vigorous activities, it is helpful if the footwear worn by the players gives full support to the foot and ankle to avoid sprains or subluxation, when vigorous movement is undertaken by the athlete. However, when the athletes are resting, on the bench, for example, it is undesirable to have the feet or ankles subject to substantial pressure, as this may inhibit circulation or the like during these rest periods.
Accordingly, a principal object of the present invention is to provide an athletic shoe which gives variable support to the foot and ankle, with increased support during periods when the user is active, and reduced or minimal support when the user is at rest. Another object of the invention is to provide an orthopedic shoe in which external air pumping arrangements are not required.